Retractable stairs

ABSTRACT

A stair unit for retracting under a structure and extending for ascending or descending between the ground and a doorway in the structure is described. A movable platform is supported on the surface by rollers and is provided with stair shaped side faces. Drive mechanism is provided for moving the platform between the extended and retracted position. A railing is provided along the outer top edge of the platform and acts as a gate across the doorway when the stair unit is in the retracted position.

[1 11 3,906,690 Sept. 23, 1975 United States Patent [1 1 lrianl a M mi SW 3,279.]31 l0/l966 3,400,502 9/ l 968 3,403.926 10/1968 Primary Examiner-Reinaldo P. Machado Attorney, Agent, or Firm-Fulwider Patton Rieber Lee & Utecht [22] Filed:

[21] Appl. No.: 478,253

Related 0.8. Application Data nuation of Ser. N

and ex- [57] ABSTRACT A stair unit for retracting under a structure [63] Conti 0. 408.173, Oct. 19, I973.

abandoned.

tending for ascending or descending between the am drep m m um 0 t. 6 wnwrm n oh m Sd t. G m r h to o P m Ph utdd S Men s M W dV om oe Or mm dov n fiosm ..l de sm a .E hdnm an? UVSC morew mhmt 84 9 NN M 2 H F5 MiA E84 s4 2 M 5 "m w on 22 "88 mm3 H H WHHZ "m h "MM Mm .L C d m UhF lill. 2 8 555 [iii References Cited provided along the outer top edge of the platform and UNITED STATES PATENTS 12/ l908 acts as a gate across the doorway when the stair unit is in the retracted position.

908,052 Wagner............. i 105/449 2.564.954 8/l95l Bresford 52/l83 8 Claims, 3 Drawing Figures RETRACTABLE STAIRS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of application Ser. No. 408,173 filed Oct. 19, 1973 and now abandoned. BACKGROUND OF THE INVENTION This invention relates to stair units and more particularly to a retractable stair unit.

In many situations structures are placed on lots of limited size. Even so it is desirable, from the standpoint of the users of the structure, to include an access road, such as a driveway, to a storage shed, car port, garage and the like, also located on the lot. Such an access road necessarily passes close to the structure due to the limited lot size or the close proximity of other structures.

In accordance with good building practice and for increased convenience to the users of a structure, an entrance from the structure to the access road and garage area is provided for convenient ingress and egress from the structure to the access road and garage area. In most cases the ground floor of the structure is raised above the ground level and stairs are necessary between the surface and the ground floor of the structure. In locating such stairs it often becomes necessary to either decrease the width of the access road in order to provide space for the stairs or to construct a very narrow or steep stairway to economize on space, at the expense of safety and convenience.

Alternate location of the entrance can be considered in custom built structures but in the case of prefabricated structures and mobile homes, relocation of an entrance is not practical. Particularly in the case of mobile homes, a single entrance is normally provided in one side of the structure. Typically the mobile home is placed on a small plot with a driveway running from the street along the side of the structure where the cntrance is located to a car port or parking area located at the rear of the plot. The provision of a permanent stairway often takes up so much area that full utilization of the access road is impossible.

Various folding and retractable steps and porches are known in the art such as for example in US. Pat. Nos. 2,1 18,557; 2,145,674; 3,008,533; 3,708,198; 3,515,406; and 3,341,223. These devices are generally designed for highly mobile vehicles such as buses, campers and the like and are designed with portability in mind. Such devices, however, are not ascetically suitable for permanent or semi-permanent structures. In addition, since they are designed for portability, the prior art devices lack the stability and safety desirable in a stair unit used for permanent and semi-permanent structures.

The present invention resides in a retractable stair unit which incorporates ease of operation, stability and safety in addition to the ascetic qualities to make the unit suitable for use with permanent and semipermanent structures.

SUMMARY OF THE INVENTION The present invention resides in an extendible and retractable stair unit that is mounted on a permanent or semi-permanent structure for access to an entrance in the structure when in an extended position and which can be readily withdrawn under the floor of the structure for utilization of the area that was occupied by the unit in the extended position. The unit is stable and safe to use and in the extended position resembles a permanently constructed stairway. As an additional safety feature, a railing is provided along the extending, outer edge of the stair unit and when the stair unit is retraeted, the railing is positioned adjacent the entrance and acts as a gate to prevent, or make more difficult, tampering with the door of the entrance. In both the extended and retracted position the stair is asthetically pleasing in appearance.

To these ends the stair unit comprises a platform having parallel front and rear faces and stair shaped side faces terminating in an upper stoop surface. The stair unit is positioned in centered relationship to the entrance of the structure and the distance from ground to the upper stoop surface is such that the stair unit will fit into a space between the ground and the undersurface of the structure.

The stair unit is movably supported by ground rollers disposed adjacent the bottom edge but inwardly thereof for concealment and the axes of the rollers are parallel to the front and rear faces so that in operation the unit is movable only in a direction normal to the vertical plane formed by the entrance of the structure. Track means are disposed beneath the structure for receiving the rollers and guiding the travel of the stair unit.

A railing is provided along the upper edge of the outer face of the stair unit. The railing functions as a supporting device when the stair unit is extended and as a gate across the structure entrance when the stair unit is retracted under the structure.

More detailed features of the retractable stair unit are found in the drive mechanism for extending and retracting the stair unit, the mounting of the guide tracks, the control of the drive means and the specific structure for mounting the ground support rollers. Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a portion of a structure and the retractable stair unit embodying the present invention in the extended position, the stair unit being partially broken away.

FIG. 2 is an enlarged side cross sectional elevation showing a portion of the structure and showing, in solid line, the stair unit in the retracted position and in broken line the stair unit in the extended position.

FIG. 3 is a plan view taken along line 33 of FIG. 2.

DETAILED DESCRIPTION As shown in the drawings the invention is embodied in a stair unit, indicated generally by the reference number 11, that is positioned adjacent a structure 12 in substantially centered relationship to a doorway 13. The illustrative structure is a mobile home which is semi-permanently positioned on a slab or the like and which has a driveway running immediately adjacent the side of the structure 12. When semi-permanently positioned, the structure 12 is parked on a concrete slab or other paved surface and is supported by suitable jacks. not shown, to take the weight off of the wheels of the structure. Normally, for insulating and ascetic purposes. siding material 15 is provided between the lower surface 14 of the structure and the ground surface to enclose the space 16 between the bottom of the structure and the ground. In such a case. the siding beneath the door is cut to provide an opening 17, which substantially conforms to the width and height of the stair unit. A drive means shown generally as 18 is located beneath the structure and is connected with the stair unit 11 for extending and retracting the stair unit 11.

When in the extended position, the stair unit It extends away from the side of the structure 12 to provide the stair area for ascending and descending from the doorway 13. A railing, shown generally as 19, is provided along the upper edge of the front face of 20 of the stair unit 11 for support while ascending and descending the stairs.

in the retracted position, the stair unit 11 is withdrawn into the space 16 between the under surface 14 of the structure 12 and the ground through the opening 17. In the retracted position, the stair unit 11 is substantially entirely nested under the structure, freeing the space formerly occupied by the stair unit, for the passage of vehicles or other uses. Also, in the retracted position, the railing l9 acts as a gate across the doorway 13 making access to a door closing the doorway 13 more difficult if someone is attempting to gain entrance into the structure while the stairs are retracted. If the door of the doorway I3 is hinged to swing outwardly from the side of the structure 12, the door cannot be opened sufficiently to allow passage of a normal sized human being, while the stair unit is retracted.

Depending on the location of the door relative to the bottom of the structure, a fixed stair 21 may be provided beneath the sill 22 of the door. The fixed stair 21 is supported by the upper surface of the stair unit 11 and is adapted for movement in relation to the upper surface of the stair unit 11.

Control means for actuating the drive mechanism are located within the structure for extending and retracting the stair unit from within and remote control means may be located in a vehicle for extending and retracting the stair unit from outside of the structure.

In accordance with the present invention, the stair unit 11 is supported by a spaced apart pair of ground support rollers 25 for movingly supporting the stair unit on the ground surface and which cooperate with the drive means 18 for the extension and retraction of the stair unit 11. The front face 20 of the stair unit 11 is preferably covered with the same siding material as used on the structure to give the stair unit 11 the appearance of permanent construction.

More specifically, as shown in FIGS. 1 and 2 the stair unit 11 comprises a stair platform 26 having substantially parallel front face 20 and rear face 27. The stair platform 26 is provided with stair shaped side surfaces 28 which are made up of one more treads 29 and risers 30. The side surfaces 28 terminate in an upper stoop surface 3] to form a porch area adjacent the doorway 13 of the structure 12. The outer edge of each tread 29 is carried by the upper surface edge of a riser 30 and the inner edge of the treads 26 by a shoulder formed by the attachment of an elongated member 32 to the outer face of each riser 30. The edges of the treads and risers are carried by the interior surfaces of the front face 20 and the rear face 27.

As shown, the second riser 30 on each side of the stair platform 26 is provided with a downwardly extending portion 33 on which is mounted the support member 23 which carries a pair of rear guide rollers 25 and an outer support roller 24. The outer end of the member 23 is co-terminus with the outer face 20 of the stair platform 26. The support roller 24 is positioned adjacent the outer end. An extension 34 is formed by the rearward extension of the member 23 beyond the rear face 27 through an opening 35 provided in the rear face 27 and a longitudinally aligned pair of the guide roilers 25 are positioned thereon for contact with the surface. An elongated channel shaped track 36 is mounted in the pavement surface as by bolts 37 for receiving and guiding the ground support rollers 25 of each member 23. The outer end of the track 36 is coterminus with the side of the structure 12 and is of sufficient length so that the guide rollers 25 are contained in the track 36 when the stair unit is retracted and extended. The support roller 24, which is longitudinally aligned with the guide rollers 25 is for support only and does not travel in the track 36. The axis of rotation of the support rollers 24 and a guide rollers 25 are disposed parallel to the front face 20 and rear face 27 of stair platform 26 so that the stair platform 26 travels normal to the vertical plane of the doorway 13 for ex tension and retraction. The tracks 36 guide the guide rollers 25 to prevent deflection of the stair platform 26 from this direction of travel.

As is shown in broken lines, in the extended position, the stair platform 26 occupies a portion of the access road blocking the path of a vehicle 38, also shown in broken lines. In the retracted position, shown in solid line, the stair platform 26 is withdrawn beneath the structure 12 and out of the path of the vehicle 38.

The stair platform 26 is extended and retracted by the drive means 18 which is operable to extend and re tract the stair platform 26 in a path normal to the vertical plane of the doorway 13. The drive means l8 comprises a reversible electric motor 39, a threaded shaft 40 driven by the motor 39 and an arm 41 threaded at one end for movement along the threaded shaft 40 and connected at the other end to the rear face 27 of the stair platform 26. The drive means [8 is positioned so that the longitudinal axes of the motor 39, and shaft 40 is aligned with the center of the stair platform 26.

As shown more specifically in FIGS. 2 and 3, the reversible electric motor 39 is suspended on the undersurface 14 of the structure 12 by a hanger 42 which is fastened as by bolts 43 to structural members of the undersurface 14. The motor 39 is electrically connected to a source of power, not shown.

Geared to the motor 39 for rotation thereby is the threaded shaft 40 which extends along the undersurface 14 of the structure 12 and is journaled at its outer end by a bushing 44 which is supported from the undersurface 14 of the structure 12 by a hanger 45. The length of the shaft 40 is such that it terminates adjacent the rear face 27 of the stair platform 26 when it is in thc retracted position. If a longer path of travel is desired, the shaft 40 can be extended and the rear face 27 of the stair platform 26 provided with an opening for receiving the shaft.

The arm 41 has a Y-shaped end 46, connected to the rear face 27 of the stair platform 26 and a bent portion 47 provided with a threaded end 48 which is in threaded engagement with the shaft 40 for travel therealong, responsive to the rotation of the shaft 40 to push the stair platform 26 into an extended position and to pull it into a retracted position. The Y-shaped portion 46 of the arm 41 distributes the motionof the arm 41 evenly across the rear face 27 of the stair. platform 26 to cooperate with the tracks 36 in maintaining the correct direction of travel for the stair platform 26. l

A stop switch 49 is provided adjacent the threaded shaft 40 for contacting the arm 41 when the stair platform 26 is retracted to break the circuit to the motor 39. This prevents the stair platform 26 from being retracted too far and doing damage to the stair unit 11 and the structure 12.

The railing 19 is provided along the top edge of the outer face and comprises upstanding posts 51 rigidly attached to the first tread 29 on each of the side surfaces 28 of the stair platform 26. Upstanding posts 52 are rigidly affixed in the outer edge of the upper stoop surface 31. Upper rails 53 and lower rails 54 are carried by the upstanding posts 51 and 52 and intermediate up standing bars 55 are carried between the railings 53 and 54 for further rigidity. When the stair platform 26 is in the fully retracted position, the railing 19 is substantially adjacent the doorway l3 and acts as a gate to prevent tampering and entrance into the structure 12.

The fixed stair 21 is positioned beneath the sill 22 of the doorway 13 for added convenience. The fixed stair 21 comprises a tread 56 extending substantially horizontally from the side of the structure 12, a pair of side members 57 and a riser 58 extending normally between the side members 57 at the outer edge thereof. A roller 59 is journaled in the inner lower edge of each side member 57 for contacting the upper stoop surface 31. In the manner support for the step 21 is provided by the stair platform 26 while allowing the stair platform 26 to be free to move between the extended position and the retracted position.

From the drawings it can be seen that sufficient clear ance is provided between the ground and the lower edges of the front face 20, the rear face 27 and the side faces 28 of the stair platform 26 to allow free movement between the extended and retracted positions. Likewise, sufficient clearance is provided between the stair shaped side faces 28 and the opening 17 provided in the side of the structure 12 to allow free movement of the stair platform 26 during its travel.

Although the inventive retractable stairs have been described specifically in connection with a semipermanent positioned mobile home, it will be clear that the invention is not so limited. It may be used in connection with structures having a crawl space between the bottom of the structure and the ground. In the case of permanent structures having basements, a suitable support structure may be constructed under the structure to support the stair unit in the retracted position.

it should also be understood that while the drive means illustrated and described is preferred, other drive mechanisms may be employed for extending and retracting the stair unit.

While in the foregoing specification, a detailed description of the specific embodiment of this invention has been set forth for the purpose of illustration. it is to be understood that many of the details herein given may be varied considerably by those skilled in the art without departing from the scope and spirit of this invention.

I claim:

1. In combination with a structure having a doorway and a space between the bottom of the structure a surface,

a stair unit positioned in centered relationship adjacent the lower edge of said doorway.

a. said stair unit comprising a stair platform having parailel front and rear faces, stair shaped side faces and an upper stoop surface. said stair shaped side faces consisting of a plurality of treads and risers ascending from the surface in stair relationship and terminating at said upper stoop surface,

one of said risersof each side surface being provided with an extension having securely affixed thereon a ground support member carrying guide rollers and support rollers for movingly supporting said stair platform,

b. a railing disposed along the upper edge formed at the juncture of said stair shaped side faces and said front face, and

c. drive means for moving said stair platform between a retracted position under the structure and an extended position adjacent the door for travel between the door and the ground surface.

2 The stair unit of claim 1 further comprising track means consisting of a channel shaped track disposed beneath said guide rollers of each of ground support members for receiving and guiding said guide rollers in a path of travel normal to the vertical plane of the door of the structure.

3. The stair unit of claim 1 wherein each of said ground support members is elongate, the longitudinal axis thereof being parallel to said side surfaces said platform, the outer end is co-terminus with said front face of said stair unit and a support roller is located adjacent the outer end, the inner end extends rearwardly the rear face of said stair unit and a pair of longitudinally aligned guide rollers are located adjacent the inner edge for travel in said trackv 4. The stair unit of claim 1 wherein said drive means comprises a motor depending from the underside of said structure and a threaded shaft is driven relationship to said motor and extending from said motor toward said stair platform, said motor and said shaft being centered with respect to the doorway, an arm having a threaded inner end engaging said shaft and longitudinally aligned therewith for travel along said shaft responsive to the rotation thereof and having a bifurcated outer end connected to said rear face of said stair unit thereby to urge said stair unit between an extended position and a retracted position responsive to the rotation of said threaded shaft.

5. The invention of claim 1 further comprising a fixed step extending from the side of the structure, said step consisting ofa tread. downwardly depending side members and front riser, the longitudinal axis of said tread being parallel to the lower edge of the doorway and the lower edges of each of said side members is provided with a roller for contacting said upper stoop surface of said stair platform for supporting said fixed step and for travel on said stoop surface while said stain platform is moving.

6. A retractable stair unit for a raised structure having an exterior surface and a lower surface spaced above a surface supporting said structure, said unit comprising:

a single platform having an upper surface, a forward face and at least one stepped side surface; surface engaging support means movably supporting said platform for travel between a retracted positerminating at said upper surface, one of said risers of each of said side surfaces being provided with an extension having securely affixed thereon a surface support member carrying rollers for movingly supporting said platform on said support surface.

8. A retractable stair unit as defined in claim 7 further including track means for receiving and guiding said rollers.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,905,590 DATED 1 Sept. 23, 1975 tNvENTORt i Leon A. Miriani It is certified that error appears in the ab0veidentitied patent and that said Letters Patent are hereby corrected as shown below Column 1, line 45, "2,145,674" to 2,145,647

Column 1, line 49, "ascetically" should be aesthetically line 57, "ascetic" should be aesthetic Column 2, line 9, "asthetically" should be aesthetically line 66, "ascetic" should be aesthetic Column 3, line 55, after "one" insert or line 60, "26" should be 29 Column, line 39, after shaft change "is" to in line 58, change "stain" to stair Signed and Scaled this seventeenth Day of February1976 [SEAL] A ttest.

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner uj'larenrs and Trademarks 

1. In combination with a structure having a doorway and a space between the bottom of the structure a surface, a stair unit positioned in centered relationship adjacent the lower edge of said doorway, a. said stair unit comprising a stair platform having parallel front and rear faces, stair shaped side faces and an upper stoop surface, said stair shaped side faces consisting of a plurality of treads and risers ascending from the surface in stair relationship and terminating at said upper stoop surface, one of said risers of each side surface being provided with an extension having securely affixed thereon a ground support member carrying guide rollers and support rollers for movingly supporting said stair platform, b. a railing disposed along the upper edge formed at the juncture of said stair shaped side faces and said front face, and c. drive means for moving said stair platform between a retracted position under the structure and an extended position adjacent the door for travel between the door and the ground surface.
 2. The stair unit of claim 1 further comprising track means consisting of a channel shaped track disposed beneath said guide rollers of each of ground support members for receiving and guiding said guide rollers in a path of travel normal to the vertical plane of the door of the structure.
 3. The stair unit of claim 1 wherein each of said ground support members is elongate, the longitudinal axis thereof being parallel to said side surfaces said platform, the outer end is co-terminus with said front face of said stair unit and a support roller is located adjacent the outer end, the inner end extends rearwardly the rear face of said stair unit and a pair of longitudinally aligned guide rollers are located adjacent the inner edge for travel in said track.
 4. The stair unit of claim 1 wherein said drive means comprises a motor depending from the underside of said structure and a threaded shaft is driven relationship to said motor and extending from said motor toward said stair platform, said motor and said shaft being centered with respect to the doorway, an arm having a threaded inner end engaging said shaft and longitudinally aligned therewith for travel along said shaft responsive to the rotation thereof and having a bifurcated outer end connected to said rear face of said stair unit thereby to urge said stair unit between an extended position and a retracted position responsive to the rotation of said threaded shaft.
 5. The invention of claim 1 further comprising a fixed step extending from the side of the structure, said step consisting of a tread, downwardly depending side members and front riser, the longitudinal axis of said tread being parallel to the lower edge of the doorway and the lower edges of each of said side members is provided with a roller for contacting said upper stoop surface of said stair platform for supporting said fixed step and for travel on said stoop surface while said stain platform is moving.
 6. A retractable stair unit for a raised structure having an exterior surface and a lower surface spaced above a surface supporting said structure, said unit comprising: a single platform having an upper surface, a forward face and at least one stepped side surface; surface engaging support means movably supporting said platform for travel between a retracted position under said lower surface of said structure and an extended position adjacent said structure; and drive means for moving said platform between said retracted position and said extended position.
 7. The retractable stair unit as defined in claim 6 wherein said platform further includes parallel front and rear faces and a pair of stair shaped side surfaces consisting of a plurality of treads and risers ascending from support surface level in stepped relationship and terminating at said upper surface, one of said risers of each of said side surfaces being provided with an extension having securely affixed thereon a surface support member carrying rollers for movingly supporting said platform on said support surface.
 8. A retractable stair unit as defined in claim 7 further including track means for receiving and guiding said rollers. 